[Nook Color General] a.fenderson:
Here's the updated list, sorted only by random 4K write speed (QD32 specified for most if not all)--as mentioned earlier, this doesn't account for the variances between benchmarking setups among us, but it should still be revealing of certain trends. Among other things: with the exception of my Transcend 32GB Class 2 card and the only two Nook Internal (eMMC) benchmarks we have, SanDisk dominates the top 23 slots, and card #24 is about 1/6th the speed (4K random writes) of the #23-listed SanDisk. There are, though, 3 SanDisk cards (2 pre-Class and one Class 2*) that fall randomly among the very poor performers.

POSTER	BRAND	CLASS	CAPACITY (GB)	4 KB RANDOM WRITE QD32 (MB/s)	NOTE
swoozle	SanDisk	2	8	1.791
a.fenderson	SanDisk	4	16	1.660	SanDisk C4 16GB 1 of 2 cards
a.fenderson	SanDisk	4	16	1.500	SanDisk C4 16GB 2 of 2 cards
Awats	SanDisk	4	16	1.391	SanDisk C4 16GB 1 of 2 cards ; fastest (onboard) reader
arwild01	SanDisk	4	8	1.369
Awats	SanDisk	4	16	1.284	SanDisk C4 16GB 2 of 2 cards ; fastest (onboard) reader
robot8	SanDisk	4	8	1.270	SanDisk C4 8GB 2 of 2 cards
robot8	SanDisk	4	8	1.259	SanDisk C4 8GB 1 of 2 cards
chinly43	SanDisk	4	16	1.257	(not via Nook) ; same card as chinly43's other listed SanDisk C4 16GB
joobu	SanDisk	4	4	1.175
angomy	Nook internal	N/A	N/A	1.116	via Nook on USB
chinly43	Nook internal	N/A	N/A	1.094	via Nook on USB
a.fenderson	Transcend	2	32	1.032
a.fenderson	SanDisk	4	4	0.898
a.fenderson	SanDisk	2	4	0.891
pchoi94	SanDisk	4	16	0.834
chinly43	SanDisk	4	16	0.769	via Nook on USB ; same as chinly43's other listed SanDisk C4 16GB
chinly43	SanDisk	2	8	0.616
a.fenderson	SanDisk	4	8	0.596
angomy	SanDisk	4	16	0.574
a.fenderson	SanDisk	N/A	2	0.269
Awats	SanDisk	4	2	0.261	SanDisk C4 2GB 1 of 2 cards ; fastest (onboard) reader
Awats	SanDisk	4	2	0.236	SanDisk C4 2GB 2 of 2 cards ; fastest (onboard) reader
joobu	Lexar	4	8	0.038
swoozle	Patriot	10	8	0.038
Ravynmagi	??	2	4	0.037
Ravynmagi	Wintech	10	16	0.036
Ravynmagi	SanDisk	2	8	0.033
Ravynmagi	Patriot	10	16	0.030
pchoi94	Kingston	2	16	0.030
chinly43	SanDisk	N/A	1	0.029
joobu	??	N/A	2	0.029
swoozle	Transcend	6	8	0.029
a.fenderson	SanDisk	N/A	1	0.028
ExploreMN	Patriot	10	16	0.018
robot8	Transcend	6	8	0.018	Transcend C6 8GB 1 of 2 cards
arwild01	Samsung(??)	4	8	0.017
Awats	Patriot	4	4	0.016	Patriot C4 4GB 1 of 2 cards ; fastest (onboard) reader
swoozle	Kingston	4	4	0.016
a.fenderson	Kingston	4	8	0.014
robot8	Transcend	6	8	0.014	Transcend C6 8GB 2 of 2 cards
Tnexus	Patriot	10	16	0.014
Awats	Patriot	4	4	0.011	Patriot C4 4GB 2 of 2 cards ; fastest (onboard) reader
chinly43	Lexar	4	8	0.011

* @Ravynmagi: do you have another reader you could use to test? I only ask because all 4 of your cards seem to have very low 4K random write speeds and all of them are within just a few one-thousandths of each other though they're very different cards. Your results include a SanDisk Class 2 8GB card, and the #1 card on the list has the same specs as this, while the only other one listed besides that still has about 19x the performance of yours. This may just show the huge variations we can sometimes expect, but the very close grouping of performance for your four very different cards leads me to think the benchmarking setup had more to do with the results than is typical.

EDIT: Two quick reviews:

1. microSD card holder: I received mine on-time and well-packaged. The item was (still is) slightly warped so that it doesn't lie perfectly flat on a table, but you hardly notice it, and it doesn't impact its function. Each of the 10 slots securely holds a microSD card, and I don't worry about them falling out even though they do rattle in the slots ever-so-slightly. The full-size SD slot also holds one SD card or most any micro-to-SD converter, though due to the nature and location of the locking tab, some of the open-backed adapters I've seen (some Transcend-branded ones for example) probably would not hold securely: Kingston and SanDisk adapters I've seen should be fine since the microSD slot is open on top but closed on the back.

2. Rocketfish eReader case: (note I bought mine on ebay as a retail return for $6.99 shipped, not from Amazon or retail) This case is exactly what I needed: it fits the Nook while it's in the Trident Aegis case, and I can slide both my SanDisk credit-card sized reader and my microSD card holder in the case on the back side of the Nook.